A long standing problem with continuous rails in railroad tracks has been the expansion and contraction of long continuous or welded rails. Typically, the entire rail in a continuous rail section is made of steel, steel alloys, brass or aluminum. These materials expand and contract significantly with the changes in temperature. For example, with a wide range in temperature variations from -20.degree. C. to +40.degree. C., the expansion or contraction of a continuous steel rail 1 km long can be 0.9 meters. This amount of expansion or contraction will distort or even buckle the track. On straightaways the track will ripple, but the thermal expansion problem is particularly severe on curves. An expanding rail at a curve will push laterally against tie plates and cause the rails in double rail track to spread more than the standard rail separation. Such spreading of the rails causes derailment of wheeled vehicles running on and guided by the rails.
Of course these problems have been solved in the past by shortening the rail sections and providing enough longitudinal separation at abutment joints in successive rails to absorb the thermal expansion of the rails. However, such joints are noisy and provide a rough ride. In addition the separated abutting joints are severe wear points for the rails, and this produces high maintenance cost for the railroad. In addition if the rail is electrified, it is difficult to maintain electrical continuity across the rail section joint from one rail to the next abutting rail.
One solution for the electrical continuity problem in the past has included electrified rail sections that have electrical cables connecting across rail joints as in U.S. Pat. No. 3,813,502. Further, composite rails are known and, for example, include rails shown in U.S. Pat. No. 2,540,433, Norwegian Patent 70654, and United Kingdom Patent Specification 256,434. None of these prior designs are directed to handling the thermal expansion in continuous surface rails. In all cases the composite rail contains fixedly attached components so that in essence they are a solid rail.